1. Field of the Invention
This invention relates to monitoring tires. In particular, it relates to a unit intended to attach on a wheel rim some of the elements necessary for monitoring tires.
2. Description of the Related Art
In most of the tire monitoring devices, one or more sensors, optionally associated with electronic components, are buried in the tire enclosure itself in order to be sensitive to the prevailing inside the enclosure, and/or to other parameters such as the temperature. In this application, these elements will generally be designated by "electric components." Also found outside the enclosure of the tire are means for assuring the connection to the vehicle, for example a coil if inductive coupling is used, or else any other suitable means.
It is necessary to make connections between these electric components buried in the tire enclosure and the means of connections placed outside the enclosure, generally radially on the inside face of the wheel rim. Consequently, it is essential to make a wheel rim bushing and then it is necessary to assure the seal at this location.
Further, industrial constraints impose designing an attachment of electric components on the wheel rim as simple and reliable as possible.
The space requirements inside the wheel rim of the braking elements and of the joints and/or suspension elements is such that any protuberance radially toward the inside of the wheel rim is proscribed.
Supports are known whose base on the wheel rim resembles a valve base: a rubber seal surrounds the opening and rests on the two inside and outside faces of the wheel rim (see for example French patent application 2 597 411). Such a fastening is bulky on the side radially inside the wheel rim. Fastenings of the nut and bolt type are known also. Generally, a seal is placed on the side radially inside the wheel rim. This poses the same space problem and the seal must therefore be attached radially inside the wheel rim, therefore inside the tire enclosure. It is necessary then to compress the seal between three parts: the wheel rim, the part equivalent to the bolt and the part equivalent to the nut. This poses tolerance problems and therefore affects reliability.